/Engine/Source/Runtime/GeometryFramework/Public/Components/DynamicMeshComponent.h
Support for Secondary triangle index buffers. When this is configured, then triangles identified by the filtering predicate function will be placed in a second set of RenderBuffers at the SceneProxy level. This can be combined with the SecondaryRenderMaterial support inUBaseDynamicMeshComponentto draw that triangle set with a different material, to efficiently accomplish UI features like highlighting a subset of mesh triangles. If Secondary triangle buffers are enabled, then we will filter triangles that pass the given predicate function into a second index buffer. These triangles will be drawn with the Secondary render material that is set in the BaseDynamicMeshComponent. Calling this function invalidates the SceneProxy.
virtual void EnableSecondaryTriangleBuffers ( [TUniqueFunction](API\Runtime\Core\Templates\TUniqueFunction)< bool(const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) *, int32)> SecondaryTriFilterFunc )